Hello, I agree with everyone else's replies.
While breeding budgies might seem rewarding, it is far more complicated then it is made out.
I have owned budgies for over seven years now, and I am only just considering breeding this year. Even now, I am still hesitant.
I would be vary of breeding the birds in your case, as birds in pet stores are usually related.
Pet stores also aren't always inclined to tell you their real ages, and, sadly, in most cases the staff put the profit before the safety of the birds.
It is also easier for pet stores birds to get and spread diseases.
Do you know if you birds are healthy?
Could they be French moult carriers?
If you still want to breed budgies, I would wait much longer than a couple months, until you feel as though you understand budgies well enough and you have everything down packed.
I would also suggest that you ask the pet store where they get their stock from, so you can pay the breeder a visit to make sure you are happy with where your birds have come from. It might also give you an insight on other aspects of the birds.
In the end, I am glad that you put the birds safety first, and have asked the bird community on their thoughts.
By the way, I hope you have a great time with your new birdies!